Airfoil



Sept; 20, 1932. R HENRY 1,878,775

.AIRFOIL Filed Dec. 31, 1950 Patented Sept. 20, 1932 UNITED STATES PATENT oFFlcE Application filed December 31, 1980. Serial No. 505,680.

This invention relates to airplanes and.

my improvements are directed to a supporting airfoil of composite character, having parts which are movable for the purpose of enabling the airfoil to have the form either of a low incidence, high speed element, or of a high incidence, low speed element.

With these and other objects in view 1 have devised a supporting airfoil having a fixed main or forward portion, and a rearward portion that is pivotally supported to be movable with relation to". the main portion for increasing the camber of the airfoil. 'Also, there is a gap provided between the airfoil portions for the flow of air to establish communication. between a region of high pressure and one of low pressure, and thereby impart additional energy to the upper surface, thus helping to maintain smooth flow over the upper surface and thereby increase the lift. 7

Also the rearward portion is divided into an upper member, which is either fixed or balanced, and a lower pivoted member that is movable to increase the camber of the airfoil, said upper member, .when separated from the lower member, presenting its entering edge to the flow of air through the gap from the pressure side.

Still further my invention comprehends an airfoil that is recessed at its rearward, under surface and provided with a pivoted portion which normally fills the recess, except for a'space lying between the leading edge of said pivotal portion, and the front wall of the recess, said pivotal portion being movable to increase the camber of the airfoil and at the same time creating a gap for the flow of air between the rearward, under surface of the airfoil and said pivotal portion; means being provided for closing the gap when the pivotal portion lies within the recess and the airfoil thereby has normal contour.

An important advantage of my invention consists in the method of dividing the trailing edge and pivoting the rearward portion to increase the camber of the lower surface without disturbing the boundary layer of the upper air stream. In ordinary flap practice the upper andlower surfaces of the flap constitute the rear portion of the profile section used and when the flap is depressed .the,air is. forced to bend around and down.

over the upper surface of the flap, and the air stream, being unable to do this except at the'smallest angles of depression, breaks away in eddies with a loss of lift and a rapid increase in drift, thereby causing a stalled condition. Other features and advantages of my invention will hereinafter appear.

In the drawing:

Figure 1 is a diagrammatic, side view of a supporting. airfoil, comprising a main front portion, a pivotal rear under portion, "and a balanced rear upper portion, the airfoil portions here being disposed in their relation as compos' g the airfoil in its low inci:

.dence, high speed attitude.

Fig. 2 is a similar view with the airfoil portions disposed in their relation as composing the airfoil in its high incidence, low speed attitude.

2, excepting that here the rear u per portion is fixed instead of balanced, an

Fig. 3 is a view corresponding with Fig.

Fig. 4: illustrates a modification wherein a I rear under portion is movable into and out of a recess formed in the airfoil.

While my invention is applicable with supporting airfoils "of different types I have herein illustrated my improvements in conjunction with a Clark Y airfoil, whose main, forward portion in the example of Figs. 1 and 2, is indicated by the reference numeral 1,

said' portion having a rearward cancavity 2,

that continues downwardly and forwardly into a convexity .3 that meets the lower pressure surface 4.

Opposed to the concavity 2 is the convexe nose or leading edge 5 of a rearward airfoil portion 5, which is ivotally supported, as at 7, the pivot being a out in the centre of pressure of said portion 6,- or forwardly thereof;

the nose 5 bemgspaced from the concavity 2 I to provide an intervening gap 8 that is maintained throughout the pivotal movement of portion 6, such movement carrying portion 6 between the attitudes thereof shown in Figs.

1 and 2 with relation to the main portion 1.

The upper surface of airfoil portion 6 has a depression 9 therein, adapted to seat an .airfoil element 10 that is movably supported as by a pivot 11, toward its forward end, so that said element may be balanced by the air flow it encounters when separated from portion 6.

In the assembled or conjunctive state of portions 1 and 6 and element 10, seen in Fig.

1, they unite to constitute the airfoil in its attitude of low incidence for high speed, the rear ends of portion 6 and element 10 forming the trailing edge of the airfoil. In this state the flow of air from the pressure surnecessitating 'an excessive inclination of the fuselage or passenger compartment. I

In Fig. 3 there appears an airfoil corresponding with that shown in Figs. 1 and 2 in all respects, except that in-Fig. 3 the element 12 is fixedly supported, instead of being pivoted like the similar element 10 of Figs. 1]

and 2. 7

The airfoil 13 appearing in Fig. 4 differs from the foregoing in that it comprises a continuous structure, from entering edge l l to trailing edge 15, but is recessed in its under, rearward surface, as at 16, and adapted-to contain, in the recess, a lower, rearward portion 17 that is pivotally supported, as at 18, said portion normally completing the airfoil profile in its low incidence, high speed attitude and serving, when swung downwardly,'as shown in dotted lines, to increase the camber of the airfoil, for low landing speed. p

The leading edge or nose 19 of the portion 17 is opposed to the forward wall 20 of recess 16 across an intervening space 21, a hinged flap 22 normally closing-the entrance to space 21. But when the airfoil portion 17 is swung downwardly, as shown in dotted lines, to increase the camber of the airfoil, then agap 23 is created between the nose 19 and the opposed surface of recess 16, and air will flow through the gap from the pressure surface of the airfoil, this air flow causing the flap 22 to uncover space 21 and exerting pressure against the surface of recess 16. i

. The movable portions of the airfoil may extend throughout the entire span thereof,

or be limited to any desirable portion thereof.

Lateral control of an airplane provided with my improved supporting airfoil has not been considered herein, because any desirable method of lateral control may be employed therewith without affecting the principle involved in my invention.

Variations within the spirit and scope of my invention are equally comprehended by the foregoing disclosure;

I claim:

1. A supporting airfoil having a repess in swung downwardly to increase the camber of the airfoil.

2. A supporting airfoil having a recess in its under surface, the top of said recess being contoured like the upper surface of an airfoil, a pivotal'airfoil member located in the rearward half of said supporting airfoil and normally lying snugly within said recess, against the top thereof, the nose of said plvotal airfoil being opposed to the forward wall of the recess over an intervening'space, and the; pivot being distanced rearwardly from said nose whereby the upper surface of said ivotal airfoil recedes from said recess to orm a passage as said pivotal airfoil is .swung downwardly to increase the camber of the airfoil, and a hinged flap to normally close said intervenin space.

New York, N. Y., ecember 29th, 1930.

' PAUL J-. HENRY. 

